the walls are filled 3 inches withHDF and 9 inches with cellulose,resulting in an R-value of 49 forthe cavity.

Since hot water accounts for 20 to 40 percent of a typical home’s energy requirement, producing it cost
effectively is important. We chose SunDrum Solar’s innovative solar water-heating system (sundrumsolar.
com). The SunDrum collectors, which fit into the underside of the PV panels, remove heat from the PV
collectors and use it to heat household water. Drawing heat from the PV also cools the crystalline cells,
making the PV system more efficient.

By using nine SunDrum collectors, we provide solar heating for about 90 percent of the two-person
household’s hot water needs. We also are gaining 10 percent in efficiency for the SunDrum-mounted PV
panels. Mike Intrieri from SunDrum Solar very graciously donated the panels and required connections
for this competition. The next nine-panel system we install, including the cost of installation on the roof,
plumbing connections and a hot water tank, is expected to cost around $6,300.

With a sale price capof $195,200 for thisaffordable, deed-restricted hometo be built in ourCoppersmith Waydevelopment, Ineeded to keep thecosts in line.

transforming the Way We Build

Based on our experience with the zero-energy Needham home, we have two more zero-energy market-rate homes on the drawing board for the Coppersmith Way development. The first is an 1,818-square-foot
(169-square-meter), two-story version of the Needham plans, called the Farmhouse. It is already under
contract for $359,900. The second is a 2,100-square-foot (195-square-meter) Greek revival plan priced at
$389,900.

The Zero Energy Challenge has inspired other projects for the company. In September we began acquiring land for an eco-village community to be developed on the Massachusetts north shore. Plans include
ZEHs, sustainable building materials and edible landscaping in a clustered village setting. In Harvard, Mass.,
we are in the permitting stage with a 24-unit mixed-income project. The intention is to reduce the energy
requirements for the homes by 90 to 100 percent, averaged across the whole development. We closed
on a four-lot conservation development in Princeton, Mass., where we have a zero-energy saltbox home
proceeding to the build-out stage.

The Zero Energy Challenge is also attracting attention beyond our commonwealth. In June, the Planet
Green television network’s “Renovation Nation” show filmed construction of our Needham zero-energy
home. Host Steve Thomas interviewed our homebuyers, Mike Intrieri and me. It was a blast. The crew
obtained footage from inside and outside the house, of the SunDrum water-heating installation and the
air-source heat pump mini-split system, and of the new homeowners blowing cellulose insulation into the
walls. The episode should appear this fall.

The Needham is currently in the final certification process with our local utility. We are on track to
receive our “0” HERS Index. The remaining five homes entered in the Zero Energy Challenge need to be
built out before a winner is announced sometime next year. At the house plan submission stage of the
competition, we were in first place, with the only 0 HERS Index. The other homes came in at 6, 18, 19,
20 and 30.

The Needham’s new owners love their zero-energy home. After purchasing it July 25, they used the
air conditioning system only once this summer, for 20 minutes, to test it. Participating in the Challenge
has revolutionized the way we approach low-energy homebuilding. It has been incredibly satisfying to
design and build a home that will essentially emit no greenhouse gases and cost the homeowner next to
nothing for their heating, air conditioning and electrical usage. If we can build an affordable zero-energy
home with adequate heating through the harsh New England winters, can a national movement to ZEHs
be far behind? r

R. Carter Scott is president of Transformations Inc. ( transformations-inc.us), a sustainable development and building company
in Townsend, Mass. He can be reached at rcarterscott@msn.com or 978.597.0542.